Lyse&Spin-QIAamp DNA Mini Kit. • About 23% of DNA is recovered using the combination of the QIAshredder and QIAamp DNA Mini kit and the Microcon® 30 column. • The extraction efficiencies of the Lyse&Spin-QIAamp DNA Mini Kit obtained by two different laboratories are similar. • The FLOQSwab™ allows releasing about 97% of the cells attached to it. Novelty Statement This research was carried out in the context of evidence evaluation considering activity level propositions when the findings are a low level of DNA obtained from touched surfaces. In such cases, knowledge of the DNA extraction kit efficiency and the efficiency of instrument to release DNA is required to evaluate the significance of DNA quantity results. Only a few studies dealt with these efficiencies. However, in these studies, the sole efficiency of the swab alone or the sole efficiency of the extraction kit alone usually remains unknown. This study aims at showing how the efficiency of DNA extraction kits and the yield of release of cells from swabs can be measured. p. 2 / 20 We also reports on the impact of the laboratory, since DNA extraction using Investigator® Lyse&Spin Basket-QIAamp DNA Mini kit from Qiagen were performed by two different persons, operating manually, from two different laboratories.